(a) Field of the Invention
The present invention relates to an in-mold label having a roughened inside surface to engage an article being molded in the mold. This roughened inside surface reduces air-entrapped blistering formed during molding, the air-entrapped blisters being between the label and the molded article. Preferably the label includes a plurality of perforations therein. To create the roughened inside surface at the time of perforating the label, the perforations are made by needles passing from the outside or exterior surface of the label through the inside surface thereby creating a plurality of burrs on the inside surface; the inside surface being the surface which will engage the article to be molded. The label also preferably, in addition to the plurality of perforations and roughened inside surface, includes adhesive in a pattern on the inside surface.
(b) Description of the Prior Art
In Takatori et al. U.S. Pat. No. 5,804,127, the reference teaches a laminating blow molding method. A resin sheet has 1 to 500 fine holes per 100 cm2 punched therein to form projections thereon as burrs. These burrs side of the resin sheet is placed in a blow mold so that the burrs face the cavity face. After the parison is blown, the mold is heated to a temperature exceeding the softening temperature of the resin sheet so squash the fine holes so that they substantially do not remain in the resin sheet. See, for example, FIGS. 5A and 5B. In Takatori, it is the non-burr side of the resin sheet is the side which will engage the hollow article being made. In contrast to the teachings of Takatori, the molds used with the labels of the present invention are cooled and not heated.
The present invention relates to an in-mold label having a roughened inside surface to engage an article being molded in the mold. This roughened inside surface reduces air-entrapped blistering formed during molding, the air-entrapped blisters being between the label and the molded article. Preferably the label includes a plurality of perforations therein. To create the roughened inside surface at the time of perforating the label, the perforations are made by needles passing from the outside or exterior surface of the label through the inside surface, or the surface which will engage the article to be molded. The label also preferably, in addition to the plurality of perforations and roughened inside surface, includes adhesive in a pattern on the inside surface, although the adhesive can be applied in a flood pattern. Generally, the label may be of paper or plastic material and have label information printed thereon. Also, an anti-static material is also preferably overprinted, if the substrate is not manufactured with anti-static qualities.
Typically, in a gravure printing process, a roll of label material has the label information, anti-static material, and adhesive printed thereon and re-rolled. Then, the roll is preferably perforated, sheeted, jogged, guillotine cut into blocks, and finally die cut into individual labels. While this is the method used by the inventors, other process can be used to produce the in-mold labels of the current invention. For example, a flexographic press could also be used. Here, as an example, the substrate could be perforated, the information printed thereon and a varnish coat applied. This would produce labels with the desired roughened surface to engage the article being molded, but, with the printing and coating after perforating, the perforation holes would not remain open. Perforation can occur anywhere in the label manufacturing process, for example, during initial production of the substrate, prior to the label printing process, after the label printing process before individual labels are produced, or after the individual labels have been cut. For example, the perforation process can be accomplished in roll to roll, or roll to sheet, or roll to rotary die cut labels in the flexographic process.
More particularly, the present invention comprises an in-mold label having a substrate, having a first surface for engaging a mold surface and an opposed second surface for engaging an article being molded, the second surface being roughened. Even further, the present invention comprises an in-mold label having a substrate having a first surface for engaging a mold surface and an opposed second surface for engaging an article being molded; the substrate having a plurality of perforations therethrough, the plurality of perforations extending from the first surface through the second surface creating a plurality of burrs on the second surface.